/*
 * Code originally from LibTomCrypt -- Licensed under the Public Domain/WTFPL2.0
 */

#include "sha256.h"
#include "sha.h"

/* Various logical functions */
#define Ch(x, y, z) (z ^ (x & (y ^ z)))
#define Maj(x, y, z) (((x | y) & z) | (x & y))
#define S(x, n) RORc((x), (n))
#define R(x, n) (((x)&0xFFFFFFFFUL) >> (n))
#define Sigma0(x) (S(x, 2) ^ S(x, 13) ^ S(x, 22))
#define Sigma1(x) (S(x, 6) ^ S(x, 11) ^ S(x, 25))
#define Gamma0(x) (S(x, 7) ^ S(x, 18) ^ R(x, 3))
#define Gamma1(x) (S(x, 17) ^ S(x, 19) ^ R(x, 10))

static void sha256_compress(sha256_context *md, const uint8_t *buf)
{
    uint32_t S[8], W[64], t0, t1;
    int i;

    /* copy state into S */
    for (i = 0; i < 8; i++) {
        S[i] = md->state[i];
    }

    /* copy the state into 512-bits into W[0..15] */
    for (i = 0; i < 16; i++) {
        LOAD32H(W[i], buf + (4 * i));
    }

    /* fill W[16..63] */
    for (i = 16; i < 64; i++) {
        W[i] = Gamma1(W[i - 2]) + W[i - 7] + Gamma0(W[i - 15]) + W[i - 16];
    }

    /* Compress */
#define RND(a, b, c, d, e, f, g, h, i, ki)        \
    t0 = h + Sigma1(e) + Ch(e, f, g) + ki + W[i]; \
    t1 = Sigma0(a) + Maj(a, b, c);                \
    d += t0;                                      \
    h = t0 + t1;

    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 0, 0x428a2f98);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 1, 0x71374491);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 2, 0xb5c0fbcf);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 3, 0xe9b5dba5);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 4, 0x3956c25b);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 5, 0x59f111f1);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 6, 0x923f82a4);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 7, 0xab1c5ed5);
    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 8, 0xd807aa98);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 9, 0x12835b01);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 10, 0x243185be);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 11, 0x550c7dc3);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 12, 0x72be5d74);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 13, 0x80deb1fe);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 14, 0x9bdc06a7);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 15, 0xc19bf174);
    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 16, 0xe49b69c1);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 17, 0xefbe4786);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 18, 0x0fc19dc6);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 19, 0x240ca1cc);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 20, 0x2de92c6f);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 21, 0x4a7484aa);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 22, 0x5cb0a9dc);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 23, 0x76f988da);
    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 24, 0x983e5152);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 25, 0xa831c66d);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 26, 0xb00327c8);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 27, 0xbf597fc7);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 28, 0xc6e00bf3);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 29, 0xd5a79147);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 30, 0x06ca6351);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 31, 0x14292967);
    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 32, 0x27b70a85);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 33, 0x2e1b2138);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 34, 0x4d2c6dfc);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 35, 0x53380d13);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 36, 0x650a7354);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 37, 0x766a0abb);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 38, 0x81c2c92e);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 39, 0x92722c85);
    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 40, 0xa2bfe8a1);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 41, 0xa81a664b);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 42, 0xc24b8b70);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 43, 0xc76c51a3);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 44, 0xd192e819);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 45, 0xd6990624);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 46, 0xf40e3585);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 47, 0x106aa070);
    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 48, 0x19a4c116);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 49, 0x1e376c08);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 50, 0x2748774c);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 51, 0x34b0bcb5);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 52, 0x391c0cb3);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 53, 0x4ed8aa4a);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 54, 0x5b9cca4f);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 55, 0x682e6ff3);
    RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], 56, 0x748f82ee);
    RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], 57, 0x78a5636f);
    RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], 58, 0x84c87814);
    RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], 59, 0x8cc70208);
    RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], 60, 0x90befffa);
    RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], 61, 0xa4506ceb);
    RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], 62, 0xbef9a3f7);
    RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], 63, 0xc67178f2);

#undef RND

    /* feedback */
    for (i = 0; i < 8; i++) {
        md->state[i] = md->state[i] + S[i];
    }
}

void sha256_init(sha256_context *md)
{
    md->curlen = 0;
    md->length = 0;
    md->state[0] = 0x6A09E667UL;
    md->state[1] = 0xBB67AE85UL;
    md->state[2] = 0x3C6EF372UL;
    md->state[3] = 0xA54FF53AUL;
    md->state[4] = 0x510E527FUL;
    md->state[5] = 0x9B05688CUL;
    md->state[6] = 0x1F83D9ABUL;
    md->state[7] = 0x5BE0CD19UL;
}

void sha256_process(sha256_context *md, const uint8_t *in, size_t inlen)
{
    size_t n;
    if (md->curlen > sizeof(md->buf)) {
        return;
    }
    if ((md->length + inlen) < md->length) {
        return;
    }
    while (inlen > 0) {
        if (md->curlen == 0 && inlen >= 64) {
            sha256_compress(md, in);
            md->length += 64 * 8;
            in += 64;
            inlen -= 64;
        } else {
            n = (((inlen) < ((64 - md->curlen))) ? (inlen)
                                                 : ((64 - md->curlen)));
            memcpy(md->buf + md->curlen, in, (size_t)n);
            md->curlen += n;
            in += n;
            inlen -= n;
            if (md->curlen == 64) {
                sha256_compress(md, md->buf);
                md->length += 8 * 64;
                md->curlen = 0;
            }
        }
    }
}

void sha256_done(sha256_context *md, uint8_t *out)
{
    int i;

    if (md->curlen >= sizeof(md->buf)) {
        return;
    }

    /* increase the length of the message */
    md->length += md->curlen * 8;

    /* append the '1' bit */
    md->buf[md->curlen++] = (uint8_t)0x80;

    /* if the length is currently above 56 bytes we append zeros
     * then compress.  Then we can fall back to padding zeros and length
     * encoding like normal.
     */
    if (md->curlen > 56) {
        while (md->curlen < 64) {
            md->buf[md->curlen++] = (uint8_t)0;
        }
        sha256_compress(md, md->buf);
        md->curlen = 0;
    }

    /* pad upto 56 bytes of zeroes */
    while (md->curlen < 56) {
        md->buf[md->curlen++] = (uint8_t)0;
    }

    /* store length */
    STORE64H(md->length, md->buf + 56);
    sha256_compress(md, md->buf);

    /* copy output */
    for (i = 0; i < 8; i++) {
        STORE32H(md->state[i], out + (4 * i));
    }
}

void sha256_hash(const uint8_t *data, size_t len, uint8_t *digest)
{
    sha256_context md;
    sha256_init(&md);
    sha256_process(&md, data, len);
    sha256_done(&md, digest);
}
